I certainly do not mean to belittle Beethoven, you'd have to be an even bigger fool than me to do that!
A way of putting is, on a scale of 1-10;
Bach is a 27 ,
Schubert and Mozart a 9.5
Beethoven a 9 .
Consider,
Bach died at 65
Beethoven at 56
Mozart at 35
Schubert at 31, and only Beethoven was perhaps as sick as he during his last years.
IMHO , if Franz had lived as long as even Mozart ,well you get it.
50 years ago European critical opinion had Schubert as a relatively minor composer, in the last 2 decades it has shifted greatly, largely to where I stand .
Most of the criticism you hear about his chamber music strikes me as like saying I wouldn't have gone out with the young Elizabeth Taylor because she was too pretty.